The Language property specifies the language which will be used to display all standard text messages within the AutoUpgrader component.

When you specifying the Language, all text in notification messages and the "Appliction update wizard" will be translated accordingly (see screenshot #2).

By default Language = wlAuto, that means that AutoUpgrader should check out current regional settings on user PC and use his native language, it's possible. If you wish to test this feature and temporary change your regional settings  go to the "Control Panel" and doubleclick "Regional Settings" icon.